Fabrication process and mechanical properties of C/SiC corrugated core sandwich panel

Abstract

Carbon fiber reinforced SiC composite is a kind of promising high-temperature thermal protection structural material owing to the excellent oxidative resistance and superior mechanical properties at high temperatures. In this work, a novel design and fabrication process of lightweight C/SiC corrugated core sandwich panel will be proposed. The compressive and three-point bending of the C/SiC corrugated sandwich panels are conducted by experiment and numerical simulation. The relative density of as-prepared C/SiC sandwich panel and the density composite material are 1.1 and 2.1 g/cm³, respectively. As the density of the C/SiC sandwich panel is only 52.3% of the bulk C/SiC, suggesting that lightweight characteristic is realized. Moreover, the C/SiC sandwich panel manifests itself as linear-elastic behavior before failure in compression and the strength is as high as 15.1 MPa. The failure mode is governed by the core shear failure and panel interlayer cracking. The load capacity under the three-point bending C/SiC composite sandwich panel is 1947.0 N. The main failure behavior is core shear failure. The stress distribution under the compression and three-point bend was simulated by FE analysis, and the results of numerical simulations are in accordance with the experimental results.

Introduction

With the development of scientific technologies, more stringent materials are needed in many new engineering, especially in aerospace, supersonic aircraft and other fields [[1], [2], [3], [4], [5], [6], [7], [8]]. The C/SiC composite is supposed to be latent high-temperature thermal protection structural material because of its excellent mechanical properties and strong resistance to oxidation [[9], [10], [11], [12]]. At present, chemical vapor infiltration (CVI) [[13], [14], [15]], reactive sintering (RB) [[16], [17], [18]] and precursor infiltration and pyrolysis (PIP) [19,20] are commonly used to prepare C/SiC composite. Compared to other methods, the PIP has numerous preponderances, for example, enhancing manufacturing efficiency and lowering fabrication temperature.

Sandwich structure is characterized by lightweight, high strength and versatility, and is widely investigated for applications in aerospace engineering. The earlier proposal of the corrugated sandwich structure has been further studied. Now, most of the corrugated sandwich panels are fabricated by common alloys or composites. As alloy constituent, aluminum, steel, stainless steel have been extensively used to fabricate corrugated core sandwich panels. Queheillalt et al. [21] prepared the corrugated core structure by employing the discharge cutting process, and the properties of the junction between the panel and core of the prepared structure were weak. Wei et al. [22] prepared ZrO₂ ceramic corrugated sandwich by using the gel injection molding process. The connection between the panel and the core is avoided to the greatest extent, and the interface between the panel and the corrugated core is relatively weak. Lin et al. [23] studied the response of porous metal sandwich plate under the impact. However, the low melting temperature of the metal and softening temperature of the composites limit their applications under the high-temperature circumstance. For supersonic air vehicles served in the high-temperature environments, if the thermal protection systems adopt the above corrugated sandwich material, it may cause irreparable damage.

Here, a new material preparation method is developed to fabricate C/SiC composite corrugated sandwich structure, which meets the demands of the thermal protection systems: high-temperature resistance (1600 °C), lightweight and high strength. Firstly, the work will introduce the fabrication process of C/SiC corrugated sandwich structures. And the most important properties, the out-of-plane compressive responses and bending properties will be explored through experiments and numerical simulation. Finally, the compressive responses and bending properties, including the strength, failure modes and stress distribution will be discussed. The conclusions of this work provide references for future research of the thermal protection system.